EP0932115A2
Expired / Lapsed
EP
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Apparatus and method for pattern recognition
Assignee: Seiko Epson Corp
•
Filing: 1999-01-14
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Granted: —
•
Expires: 2019-01-14
Abstract
Abstract A method and an apparatus for pattern recognition are described. Features characterizing at least two significant portions or regions of the printed pattern on a model document are extracted from a scanned-in image of the model document. Statistical characteristics of each significant region are calculated from the extracted features and saved in a memory. In addition, geometrical relationships, e.g. distances and angles, between the regions are also saved in a memory. The geometrical relationships are represented by the coordinates of the regions in a predetermined coordinate system, e.g. the x-y coordinate system corresponding to the scan area on the platen of a scanner. When a new or trial document is scanned and examined through a search window, features are extracted from the search window blocks and compared to the statistical characteristics of the model document previously stored in memory. If there is a match, the coordinates of the search window having the matching features in the trial document are recorded in a candidate list. After the entire trial document has been processed, the geometric relationships between the window blocks on the candidate list are compared with the geometrical relationships of the matching significant region blocks of the model document and if the relationships correspond the trial document is considered a match.
Inventors
- 👤 Shang-Hung Lin
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 11:24
CPC Classifications
G; G06; G06V; G06V30/00; G06V30/40; G06V30/41; G06V30/414; G06V10/00; G06V10/70; G06V10/74; G06V10/75; G06V10/751; G06V10/7515
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
190 words
An apparatus for recognizing patterns in a trial
image comprising: a feature extractor for extracting features from window
image blocks in said trial image, said window image blocks
having respective coordinates in a coordinate space; a memory for storing characteristics of regions of a
model image, said regions having respective coordinates in
said coordinate space; a similarity comparator for comparing said extracted
features to said characteristics of said regions and for
indicating features similar to said regions; a candidate list for storing coordinates of window
image blocks with features indicated by said comparator as
having similar regions and for storing coordinates of
corresponding similar regions; an analyzer for determining a window image block
geometric relationship between at least two window image
blocks in said candidate list from said respective
coordinates and for determining a region geometric
relationship between at least two corresponding regions from
said respective coordinates; and a geometry comparator for comparing said window image
block geometric relationship to said region geometric
relationship for recognizing said trial image as
corresponding to said model image when said window image
block geometric relationship is the same as said region
geometric relationship.
Claim 2
Dependent Claim
26 words
An apparatus as in Claim 1 wherein said feature
extractor comprises a histogram equalizer for redistributing
pixel gray levels in an area of said trial image.
Claim 3
Dependent Claim
30 words
An apparatus as in Claim 2 wherein said feature
extractor comprises an x-y direction projector for forming a
feature vector from said trial image area with redistributed
pixel gray levels.
Claim 4
Independent Claim
30 words
An apparatus as in any one of the preceding claims,
further comprising a scanner for scanning in a model image
and an image buffer for storing a scanned-in model image.
Claim 5
Dependent Claim
36 words
An apparatus as in Claim 4 further comprising a
region extractor for extracting region image blocks from said
model image stored in said image buffer and a region buffer
for storing said extracted region image blocks.
Claim 6
Dependent Claim
30 words
An apparatus as in Claim 5 comprising an affine
transformer for translating and rotating said region image
blocks to create additional region image blocks for storage
in said region buffer.
Claim 7
Dependent Claim
24 words
An apparatus as in Claim 6 wherein said feature
extractor is coupled to said region buffer for extracting
region features from said model image.
Claim 8
Dependent Claim
26 words
An apparatus as in Claim 7 wherein said feature
extractor comprises a histogram equalizer for redistributing
pixel gray levels in an area of said model image.
Claim 9
Dependent Claim
30 words
An apparatus as in Claim 8 wherein said feature
extractor comprises an x-y direction projector for forming a
feature vector from said model image area with redistributed
pixel gray levels.
Claim 10
Dependent Claim
22 words
An apparatus as in Claim 9 further comprising a
vector statistical analyzer for forming statistical vectors
characterizing regions of said model image.
Claim 11
Independent Claim
39 words
An apparatus as in any one of the preceding claims,
wherein said analyzer comprises a distance calculator for
calculating a distance between said at least two window image
blocks and a distance between said at least two corresponding
regions.
Claim 12
Dependent Claim
35 words
An apparatus as in Claim 11 wherein said analyzer
comprises an angle calculator for calculating an angle
between said at least two window image blocks and an angle
between said at least two corresponding regions.
Claim 13
Independent Claim
165 words
A method for recognizing patterns in a trial image
comprising: extracting features from window image blocks in said
trial image, said window image blocks having respective
coordinates in a coordinate space; storing characteristics of regions of a model image,
said regions having respective coordinates in said coordinate
space; comparing said extracted features to said
characteristics of said regions and indicating features
similar to said regions in a similarity comparator; storing coordinates of window image blocks with
features indicated by said comparator as having similar
regions and storing coordinates of corresponding similar
regions; determining a window image block geometric relationship
between at least two window image blocks from said respective
coordinates and determining a region geometric relationship
between at least two corresponding regions from said
respective coordinates; and comparing said window image block geometric
relationship to said region geometric relationship and
recognizing said trial image as corresponding to said model
image when said window image block geometric relationship is
the same as said region geometric relationship.
Claim 14
Dependent Claim
29 words
A method as in Claim 13 wherein said feature
extracting step comprises histogram equalizing an extracted
feature for redistributing pixel gray levels in an area of
said trial image.
Claim 15
Dependent Claim
30 words
A method as in Claim 14 wherein said feature
extracting step comprises x-y direction projecting said
redistributed pixel gray levels of said trial image area and
forming a feature vector.
Claim 16
Independent Claim
30 words
A method as in any one of the preceding claims 13 to 15,
further comprising scanning in a model image and storing said
scanned-in model image in an image buffer.
Claim 17
Dependent Claim
32 words
A method as in Claim 16 further comprising
extracting region image blocks from said model image stored
in said image buffer and storing said extracted region image
blocks in a region buffer.
Claim 18
Dependent Claim
26 words
A method as in Claim 17 comprising translating and
rotating said region image blocks to create additional region
image blocks for storage in said region buffer.
Claim 19
Dependent Claim
14 words
A method as in Claim 18 comprising extracting
region features from said model image.
Claim 20
Dependent Claim
31 words
A method as in Claim 19 wherein said region feature
extracting step comprises histogram equalizing an extracted
region feature to redistribute pixel gray levels in an area
of said model image.
Claim 21
Dependent Claim
36 words
A method as in Claim 20 wherein said region feature
extracting step comprises x-y direction projecting said
histogram equalized region feature and forming a feature
vector from said model image area with redistributed pixel
gray levels.
Claim 22
Dependent Claim
22 words
A method as in Claim 21 further comprising
statistically analyzing feature vectors and forming
statistical vectors characterizing regions of said model
image.
Claim 23
Independent Claim
39 words
A method as in any one of the preceding claims 13
to 22, wherein said determining step comprises calculating a
distance between said at least two window image blocks and a
distance between said at least two corresponding regions.
Claim 24
Dependent Claim
32 words
A method as in Claim 23 wherein said determining
step comprises calculating an angle between said at least two
window image blocks and an angle between said at least two
corresponding regions.
Claim 25
Independent Claim
43 words
A medium readable by a machine embodying a program
of instructions executable by said machine to perform a
method of recognizing patterns in a trial image, said pattern
recognizing method being in accordance with any
one of the preceding claims 13 to 24.
Claim 26
Independent Claim
255 words
A system for comparing a trial document to a model
document and for preventing copying of a trial document
matching said model document comprising: a scanner for scanning a model document and a trial
document; a feature extractor for extracting trial document
features from window image blocks in said trial document and
for determining characteristics of regions of said model
document, said window image blocks having respective
coordinates in a scan coordinate space; a memory for storing said characteristics of regions of
said model document, said regions having respective
coordinates in said scan coordinate space; a similarity comparator for comparing said extracted
features to said characteristics of said regions and for
indicating features similar to said regions; a candidate list for storing coordinates of window
image blocks with features indicated by said comparator as
having similar regions and for storing coordinates of
corresponding similar regions; an analyzer for determining a window image block
geometric relationship between at least two window image
blocks in said candidate list from said respective
coordinates and for determining a region geometric
relationship between at least two corresponding regions from
said respective coordinates; and a geometry comparator for comparing said window image
block geometric relationship to said region geometric
relationship for recognizing said trial document as matching
said model document when said window image block geometric
relationship is the same as said region geometric
relationship; a printer; an action unit coupled to said geometry comparator and
said printer for preventing copying of said trial document if
it matches said model document.
Claim 27
Independent Claim
266 words
A system for comparing a trial document to a model
document and for preventing copying of a trial document
matching said model document comprising: an input device for inputting an image of said model
document and an image of said trial document; a feature extractor for extracting trial document
features from window image blocks in said trial document and
for determining characteristics of regions of said model
document, said window image blocks having respective
coordinates in an input device coordinate space; a memory for storing said characteristics of regions of
said model document, said regions having respective
coordinates in said input device coordinate space; a similarity comparator for comparing said extracted
features to said characteristics of said regions and for
indicating features similar to said regions; a candidate list for storing coordinates of window
image blocks with features indicated by said comparator as
having similar regions and for storing coordinates of
corresponding similar regions; an analyzer for determining a window image block
geometric relationship between at least two window image
blocks in said candidate list from said respective
coordinates and for determining a region geometric
relationship between at least two corresponding regions from
said respective coordinates; and a geometry comparator for comparing said window image
block geometric relationship to said region geometric
relationship for recognizing said trial document as matching
said model document when said window image block geometric
relationship is the same as said region geometric
relationship; an output device; an action unit coupled to said geometry comparator and
said ouput device for preventing copying of said trial
document if it matches said model document.
Claim 28
Dependent Claim
26 words
A system as in Claim 27 wherein said input device
is a digital camera, a computer or a scanner, and said output
device is a printer.
References Cited (Backward Citations)
No citation records indexed.
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